Institute of Research and Agrofood technology (IRTA) Postharvest Program, Edifici Fruitcentre, Parc Científic i Tecnològic Agroalimentari de Lleida, 25003 Lleida, Catalonia, Spain.
IRTA, Plant In Vitro Culture Laboratory, Fruticulture Program, Barcelona, Spain.
J Exp Bot. 2022 Nov 2;73(19):6971-6982. doi: 10.1093/jxb/erac346.
Soil bacteria promote plant growth and protect against environmental stresses, but the mechanisms involved remain poorly characterized, particularly when there is no direct contact between the roots and bacteria. Here, we explored the effects of Pseudomonas oryzihabitans PGP01 on the root system architecture (RSA) in Arabidopsis thaliana seedlings. Significant increases in lateral root (LR) density were observed when seedlings were grown in the presence of P. oryzihabitans, as well as an increased abundance of transcripts associated with altered nutrient transport and phytohormone responses. However, no bacterial transcripts were detected on the root samples by RNAseq analysis, demonstrating that the bacteria do not colonize the roots. Separating the agar containing bacteria from the seedlings prevented the bacteria-induced changes in RSA. Bacteria-induced changes in RSA were absent from mutants defective in ethylene response factor (ERF109), glutathione synthesis (pad2-1, cad2-1, and rax1-1) and in strigolactone synthesis (max3-9 and max4-1) or signalling (max2-3). However, the P. oryzihabitans-induced changes in RSA were similar in the low ascorbate mutants (vtc2-1and vtc2-2) to the wild-type controls. Taken together, these results demonstrate the importance of non-volatile signals and redox mechanisms in the root architecture regulation that occurs following long-distance perception of P. oryzihabitans.
土壤细菌能促进植物生长并抵御环境胁迫，但相关机制仍知之甚少，特别是当根系与细菌没有直接接触时。在这里，我们研究了 Pseudomonas oryzihabitans PGP01 对拟南芥幼苗根系架构（RSA）的影响。当幼苗在 P. oryzihabitans 存在的情况下生长时，侧根（LR）密度显著增加，同时与改变养分运输和植物激素反应相关的转录本丰度也增加。然而，通过 RNAseq 分析在根样本上未检测到细菌转录本，表明细菌不会定植在根上。将含有细菌的琼脂与幼苗分离，可防止细菌引起的 RSA 变化。在乙烯反应因子（ERF109）、谷胱甘肽合成（pad2-1、cad2-1 和 rax1-1）和独脚金内酯合成（max3-9 和 max4-1）或信号转导（max2-3）缺陷的突变体中，不存在细菌诱导的 RSA 变化。然而，在低抗坏血酸突变体（vtc2-1 和 vtc2-2）中，PGP01 诱导的 RSA 变化与野生型对照相似。综上所述，这些结果表明，在远距离感知 P. oryzihabitans 后，非挥发性信号和氧化还原机制在根系架构调控中具有重要作用。
